lecture 14 Flashcards
(121 cards)
1
Q
five main types of blood vessels
A
arteries
arterioles
capillaries
venules
veins
2
Q
layers of blood vessels are called
A
tunics
3
Q
tunica interna
A
endothelial lining in direct contact with blood
4
Q
tunica media
A
intermediate layer of smooth muscle and CT
5
Q
tunica externa
A
surrounding CT layer
6
Q
tunica interna function
A
facilitates exchange by diffusion
- contains large pores to allow large molecules to diffuse
7
Q
what surrounds the endothelium of blood vessels and what does it do
A
basement membrane that anchors it down and provides strength
8
Q
tunica media function
A
varies between vessel type
mediates vasoconstriction and vasodilation
- makes vessels extensible and elastic
9
Q
tunica externa function + facts
A
contains many nerves
- made of collagen and elastic fibres
10
Q
vasa vasorum
A
tiny vessels that service the smooth muscle of big vessels like the aorta
11
Q
capillary layers
A
tunica interna
basement membrane
12
Q
elastic arteries
A
made of elastic fibres in tunica media/interna and a thin layer of smooth muscle
- push blood from the heart during diastole
near the heart, allows them to maintain constant pressure
13
Q
pressure reservoir
A
blood stretches elastic fibres in tunica media and interna
creates potential energy for blood to move
14
Q
example of elastic arteries
A
aorta, pulmonary trunk
15
Q
muscular arteries
A
thicker layer of smooth muscle
- loose tunica externa (allows constriction/dilation)
- aka distributing arteries
16
Q
why are muscular arteries aka distributing arteries
A
because they move blood into smaller arterioles
17
Q
anastomoses definition
A
places that vessels of related function joint one another
18
Q
anastomoses function
A
provide bypass methods for blood to tissues during collateral circulation
(eg. large intestine, many branches of arteries stemming from the celiac trunk)
19
Q
end arteries
A
arteries without anastomoses
20
Q
necrosis
A
messy tissue death
21
Q
example of an end artery
A
brachial artery
22
Q
arterioles
A
microscopic arteries
23
Q
arteriole make up
A
50% of diameter is wall
has elastic lamina in tunica interna
- tunica media - 1-2 layers of ring shaped smooth muscle`
24
Q
metarterioles
A
narrowed sections of arterioles
25
precapillary sphincter
can pinch of capillaries
26
nerves in the tunica externa of metarterioles function to:
regulate vessel diameter
27
capillary structure
lack tunica externa and media
28
capillary bed
a branch of metarterioles that lead into 10-100 capillaries
29
routes for blood to go from metarterioles to venules
- through capillaries
- through a thoroughfare channel
30
route for blood - through capillaries
(+exit and what teh circulation is called)
blood enters capillary bed
- exits via postcapillary venules
- called microcirculation
31
vasomotion
contraction and relaxation of precapillary sphincters to regulate blood flow through the beds
32
route for blood - through a thoroughfare channel
permits direct flow from metarteriole to venule
sphincters are closes, one way passage, blood does not to to extensive branches of capillaries
33
3 types of capillaries
continuous
fenestrated
sinusoids
34
continuous capillaries
- smooth continuous epithelium
- no holes, just intercellular clefts
- found in organs of CNS, lungs, muscle, and skin
35
intercellular clefts
division points in capillaries between adjacent endothelial cells
36
fenestrated capillaries
- endothelium has pores called fenestrations that permit diffusion of proteins and such
- found in kidneys, small intestine villi, eyes, endocrine glands
37
sinusoid capillaries
wider and twistier
- little/no basement membrane
- large pores
- where RBCs enter circulation from bone marrow
- found in liver, spleen, and other glands
38
fenestrations
pores found between endothelial cells in capillaries
fenestrated and sinusoid capillaries only
39
muscular veins can:
can withstand lots of pressure
40
veins - facts
10% of diameter is wall
- change shape as they merge
- thick tunica externa that contributes to distensibility
- systemic - act as blood reservoirs
41
blood reservoirs
places in the body that store large amounts of blood
eg. abdominal veins, skin
42
capillary exchange
movement of substances between blood and interstitial fluid
43
3 mechanisms of capillary exchange
diffusion
transcytosis
bulk flow
44
capillary exchange - diffusion
through fenestrations, cle
45
capillary exchange - transcytosis
(eg...)
- rare method
eg. insulin entering fetal blood stream
46
capillary exchange - bulk flow
collective movement of large volumes of molecules from high pressure to low pressure
- regulates volumes of blood and interstitial fluid
- regulated by fluid pressures
47
filtration
movement from blood into interstitial fluid in bulk flow
48
reabsorption
movement from interstitial fluid into blood in bulk flow
49
net filtration pressure (NFP)
difference between filtration and reabsorption
this is what bulk flow is driven by
50
NFP consists of (2)
hydrostatic and osmotic pressures
51
Blood hydrostatic pressure (BHP)
pressure of water in blood plasma pushing on endothelium
- caused by forceful ejection of blood from ventricles
- higher at arterial end than venous end in capillaries
biggest force in filtration
52
interstitial fluid hydrostatic pressure (IFHP)
pressure of water from interstitial fluid pushing on basement membrane of capillaries
- very weak
- constant pressure across all ends
- weak force in reabsorption
53
Blood colloid osmotic pressure (BCOP)
pressure exerted on solutes and proteins in blood that pulls on water in interstitial fluid
- constant across due to constant protein in blood
- strongest force in reabsorption
54
interstitial fluid osmotic pressure (IFOP)
pressure exerted by solutes in interstitial fluid that pulls on water in blood plasma
- very weak force in filtration
55
forces of bulk flow (mmHG)
BHP - 35/16mmHg out
IFHP - 1 mmHg in
BCOP - 26 mmHg in
IFOM - 0 mmHg out
56
Net filtration pressure equation
NFP = (BHP+IFOP) - (BCOP+IFHP)
NFP = (filtration) - (absorption)
taken at both the arterial and venous ends
57
what happens to filtered fluid?
85% is reabsorbed
15% taken up by lymph vessels and returned to circulation
58
edema
increase in interstitial fluid volume
59
lymph edema
failed of lymphatic vessels to filter properly
60
how can protein deficiency lead to edema
lack of protein will cause a decrease in BCOP, meaning a decrease in reabsorption, leaving a higher chance for fluid buildup
61
hemodynamics
the study of the forces that affect blood flow in the body
62
blood flow
volume of blood flowing through a given tissue at a given time in mL/min
total blood flow = CO
63
perfusion
extent of blood flow to a particular area
64
what modulates blood flow? (2)
blood pressure
vascular resistance
65
blood pressure
hydrostatic pressure that blood exerts on blood vessel walls
- highest in aorta
- generated by contraction of the ventricles
66
systolic blood pressure
highest BP in arteries during cardiac systole
67
diastolic BP
lower BP in arteries during cardiac diastole
68
units for blood pressure
millimetres of mercery
mmHg
69
arterial end of capillaries mmHg
35
70
venous end of capillaries mmHg
16
71
entry into the right atrium mmHg
0
72
factors that affect blood pressure
changes of blood volume over 10%
73
if you are retaining a lot of water, what happens to BP
increases
74
resistance
forces of friction that oppose blood flow through a vessel
75
vascular resistance is affected by: (3)
diameter of vessel lumen
blood viscosity
total vessel length
76
how does lumen diameter affect vascular resistance?
if the lumen is smaller, there is more surface area, more blood touches the lumen walls, increasing resistance
77
increased VR =
increase BP
78
how could the body increase the rate of venous return?
it could pump blood more forcefully from the heart
- exercise
- if BP increased at right atrium, rate of venous return would DROP
79
how does blood return to the heart when we sleep?
the respiratory pump
80
what increases venous return? (4)
increases blood volume
skeletal pump
respiratory pump
vasoconstriction
81
what increases heart rate (2)
decreased parasympathetic impulses
- increased sympathetic impulses and hormone release (fight of flight)
82
what increases stroke volume (2)
increased venous return
- increased parasympathetic impulses (decreased HR)
83
what increases cardiac output (2)
heart rate
stroke volume
84
what increases blood viscosity
increased number of red blood cells
85
what increases total blood vessel length
increased body size as in obesity
86
what increases systemic vascular resistance (3)
increased blood viscosity
increased vessel length
decreased vessel radius (vasoconstriction)
87
what increases mean arterial pressure (2)
increased cardiac output
increase vascular resistance
88
blood velocity
the speed at which blood flows
89
what influences blood velocity
vascular resistance
90
why is blood flow slow in capillaries
greater surface area = increases resistance
91
cardiovascular centre can signal for increased or decreased: (2+1)
heart rate
heart contractility
can also stimulate vaso dilation/constriction
92
RAA (renin-angiotensis-aldosterone system) affect on blood pressure
increases BP by decreasing urination
93
epinephrine/norepinephrine affect on BP
increase BP by increasing calcium in cytosol of cells
94
ADH (anti-diuretic hormone) affect on BP
increases BP by vasoconstriction
95
ANP (atrial natriuretic peptide) affect on BP
decreases BP by vasodilation and decrease reabsorption in kidneys
96
autoregulation of flow
blood vessels can change their own physiology to meet metabolic demand
97
2 inputs of autoregulation
physical changes
vasoconstrictors/dilators
98
physical constrictors - input of autoregulation
stretching of an elastic artery or vein
increased organ activity = more blood to that organ
99
vasodilators/constrictors - input of autoregulation
substances that increase/decrease vessel diameter (NO, K+)
100
systemic vs pulmonary - response to low O2
systemic - dilates to increase tissue perfusion
pulmonary - constricts to ensure only undamaged alveoli are used to oxygenate blood
101
shock
lack of o2 and nutrients to meet the bodies needs
must affect whole body
102
different kinds of shock (6)
hypovolemic shock
cardiogenic shock
anaphylatic
neurogenic
septic
obstructive
103
hypovolemic shock
cause by excessive dehydration
output - decrease blood vol
104
cardiogenic shock
damage to the heart
output - inability to pump
105
anaphylactic shock
excessive histamine production and vasodilators
output - decreased BP
106
neurogenic shock
head trauma
output - inability to sense and respond to BP changes
107
septic shock
bacterial toxins cause excessive vasodilation
output - decreased BP
108
obstructive shock
block to circulation
109
physiological responses to shock (4)
stimulate RAA pathway (increase blood vol)
release ADH (increase blood vol)
stimulate sympathetic nervous responses (vasoconstriction/dilation)
release local vasodilators (increase blood flow to specific tissues)
110
hypertension and its risks
persistently elevated BP
increased risk of heart failure, kidney disease, strokes
90-95% of cases are untraceable
111
circulatory routes (2)
systemic
pulmonary
112
function of systemic circulation
distribute O2 blood from left ventricle to all the bodys tissues
returns deoxy blood to the right atrium
113
4 arteries that service the head
vertebral arteries (2)
carotid arteries (2)
114
what ensures the brain is perfused properly
the great number of anastomoses in the brain
115
carotid-basilar artery anastomosis
joining of the posterior cerebral arteries and the posterior communicating arteries to the basilar artery
116
hepatic portal circulation
carries blood from GI tract to liver
117
hepatic capillaries are mostly
sinusoids
118
proper hepatic artery
brings oxy blood to the liver
119
pulmonary circulation function
brings deoxy blood from right ventricle to the alveoli for oxygenation
routes oxy blood to the left atrium
DOES NOT provide oxygen to the lung tissues
120
bronchial circulation
oxygenates lung tissues
121
the placenta is formed from both:
maternal and fetal tissues
